The present invention relates to a broadband communication device. More particularly, the present invention provides a broadband restricted MMI-based polarization beam splitter with low loss and high extinction ratio for a broad wavelength band of 1270 nm-1330 nm.
Over the last few decades, the use of broadband communication networks exploded. In the early days Internet, popular applications were limited to emails, bulletin board, and mostly informational and text-based web page surfing, and the amount of data transferred was usually relatively small. Today, Internet and mobile applications demand a huge amount of bandwidth for transferring photo, video, music, and other multimedia files. For example, a social network like Facebook processes more than 500 TB of data daily. With such high demands on data and data transfer, existing data communication systems need to be improved to address these needs.
As an important integrated optics device, a compact polarization beam splitter (PBS) can be used to achieve polarization independent operation of photonic integrated circuits (PICs) and linear optical quantum information technology. PBS has become a key element for polarization management in next polarization-independent Si Photonics Circuit. A preferred PBS should simultaneously have short device length, high extinction ratios, low insertion loss, broadband operation, stability, simple structure and high fabrication tolerances. Compact, simple and broadband PBS on silicon-on-insulator (SOI) is crucial for Coarse Wavelength Division Multiplexing (CDWM) in the 1300 nm window. The state-of-art designs for the PBS are mostly based on asymmetrical Mach-Zehnder interferometer (MZI), single directional coupler. The conventional PBS has at least one or more the following issues of low in extinction ratio between orthogonal polarizations Transverse Magnetic (TM) mode and Transverse Electric (TE) mode, large in foot print, or wavelength-sensitive in 1300 nm window. Although immense amount of concrete researches have been done, the issues mentioned above remain to be unsolved.
Therefore, it is desired to develop improved compact polarization beam splitter that is wavelength insensitive across entire 1300 nm O-band window for the integrated Si photonics circuits.